If a turbine component in a turbomachine, such as an aircraft engine, experiences a shaft breakage, the rotor must be prevented from moving uncontrollably out of the position thereof and from radially, respectively axially penetrating the housing surrounding it. For that reason, aircraft engines are generally provided with a run-in system that is supposed to brake the kinetic energy of the rotor by selectively, axially running in the shaft fragments to the point where no fragments can be hurled through the housing to the external environment. Known run-in systems are configured in the turbine, for example, between an outer shroud of a rotor blade row and the blades of a following guide vane row.
The U.S. Patent Application 2008/0289315 A1 describes an alternative run-in system where the downstream hub region of a rotor blade row has a circumferential toothed rim configured therein that engages into a guide vane-side run-in coating in response to a shaft breakage. This run-in system does, in fact, relieve the guide vane blades, however, the toothed rim also creates a plurality of point contacts between the toothed profile and the run-in coating. This run-in system can be produced in a mechanical machining process. Alternatively, a subsequent mounting of the toothed rim and a subsequent application of the run-in coating are possible. Moreover, both the mechanical machining, as well as the subsequent binding process constitute time-consuming manufacturing variants.
The U.S. Patent Application 2009/0126336 A1 describes a run-in system where a radially inner, guide vane-side, ring-shaped run-in coating is produced from a granular material by sintering under the action of temperature and pressure, respectively is subsequently bound. However, the sintering and, in particular, the subsequent binding of the run-in coating are relatively expensive. In particular, a faulty binding can lead to an abrasion, respectively breaking-away of the run-in coating, and, consequently, to an uncontrolled braking of the broken shaft pieces.